1. Field of the Invention
The present invention relates to rail joints for the connection of two rails with different profile sections.
2. Description of the Related Art
A railroad way is formed by joining two sets of parallel rails together, each set of rails formed of a number of rails connected lengthwise at their adjoining aligned ends. When one of the installed rails required replacement due to breakage, damage or completion of useful service life, the old installed rail has been replaced with a replacement or substitute rail, which could be a new or a used rail. In such cases, the replacement or substitute rail has often been a different profile than that of the connecting rail to which connection was made. Rail joints have been used to maintain adjoining ends of rails in place when the rails have differing characteristics, such as different height, weight or profile. The profile of a rail is its shape in vertical cross-section, perpendicular to its longitudinal or length dimension. Rail joints have been provided in an attempt to compensate for transitions between adjoining rail ends with different profiles, but problems have remained.
So far as is known, the webs and heads of existing track at the rail ends were formed with curved surfaces, and the joints had generally flat surfaces except at surfaces formed on upper and lower edge portions. However, problems have been found to occur. Due to the rolling process of forming rails, there were minor variations in the various angles and ratios at the rail ends as well as elsewhere along their length. The dimensions and slope of the central flat portion of the web, and the curved surfaces below the head portion and the base, as well as their relative spacing, usually had minor variations between different rails, even if of the same nominal size. Similarly, the existing joints typically also had variation in dimensions and shape, even if of the same nominal size and height.
It was thus difficult to achieve a proper match and engagement between the rail ends and joints when replacement rails were being installed. In situations where a properly fitted match between the contact surfaces of the rails and the joint was not achieved, the assembled structure often exhibited less relative strength, and the assembled structure had a reduced service life.